The present invention relates to the field of mobile fire engines, and particularly to fire engines having extension ladders. The present invention is directed to a system of stabilizing the fire engine when the extension ladder is in use, such that an extension ladder of substantial length may be employed and operated through a full range of motion. The present invention is also directed to a fire engine utilizing the stabilizing system, wherein the stabilizing system and extension ladder are located for maximum stabilization.
Fire engines are well known machines utilized in fighting fires. Typically, fire engines are designed to carry multiple occupants and a plethora of equipment that may be needed at a fire scene. Fire engines are generally equipped with pumping systems that can pump water through hoses to the location of a fire. These pumping systems normally communicate with a water tank located within the body of the fire truck, and are also adapted to pump water from a city water supply via, for example, a fire hydrant, or from a body of water.
In small towns, or in areas without large buildings, these fire engines may simply carry hand operated step or extension ladders to allow the firefighters called to a fire to reach the necessary areas. However, in large cities or areas with buildings and other structures of substantial height, hand-operated ladders have insufficient reach to allow access to all parts of a structure. To this end, powered extension ladders were developed and mounted to fire engines so that firefighters and their equipment could reach elevated areas. These powered extension ladders permit firefighters to be elevated to a position wherein they can attack a fire from above. Hoses and other equipment may be transported by the ladder along with the firefighters. Such extension ladders have also proven useful in effecting the rescue of occupants from burning buildings. As fires may start in the lower levels of tall buildings, it is sometimes the case that occupants on upper levels will not become aware of a fire until the fire is in such an aggravated state that passage out of the building through the lower levels is impossible. In such a case, the powered extension ladder of the fire engine can be used to remove trapped occupants through upper level windows. Of course, rescue operations are not limited to the victims of fire, and such fire engines may be called whenever a high elevation rescue is necessary.
As we continue to construct buildings of increasing height, however, longer extension ladders are needed to reach the rising upper levels. Unfortunately, longer ladders are also heavier, which poses a problem not only as to ladder construction, but also to the stability of the fire engines to which they are mounted. The weight of these longer ladders combined with the various positions into which they may be placed, may exert such a moment on the fire engine to which they are attached that the fire engine can become unstable. For this reason, stabilizing systems have been added to these fire engines, wherein additional bracing points are provided between the fire engine and the ground to maintain stability while the extension ladder is in use.
There are known fire engines having powered extension ladders of 100 to 110 feet. However, these known fire engines are limited in that they are unable to move the ladder through a full range of motion due to the instability imparted thereby. Even when employing remote stabilizers, these known fire engines have required that the attached ladders be confined to a limited range of motion. Especially problematic has been the situation wherein the ladder is placed in an extended position and rotated to project outward substantially laterally to the length of the fire engine. This situation is further exacerbated as the angle of the ladder approaches horizontal. It is in this position that the most severe moment is imparted to the fire engine, as the weight of the ladder is disposed at close to a right angle to its attachment on the fire engine. For this reason, known fire engines with extension ladders in this length range prohibit placement of the ladder in such a position, thereby circumventing any dangers that could result from the possible instability of the fire engine. Therefore, what is. needed is a fire engine having an extension ladder of 100 feet or more, wherein the extension ladder may be moved through a full range of motion.
The fire engine of the present invention satisfies the need for a fire engine having an extension ladder of a length in excess of 100 feet, wherein the extension ladder may be safely moved through a full range of motion while the ladder is fully extended without. The fire engine of the present invention has an extension ladder mounted thereto, which extension ladder can be extended to a length of approximately 110 feet. The extension ladder is mounted to a turntable on the fire engine, thereby imparting 360 degrees of rotation to the extension ladder. The extension ladder is moveable from a storage position that is substantially horizontal to the ground, to a fully upright position that is substantially perpendicular to the ground. The extension ladder can be placed in any rotational position regardless of the orientation of the extended ladder with respect to the ground, thus, the ladder may be fully extended laterally from the fire engine, even when the ladder is substantially horizontal to the ground. Not only can the ladder of the fire engine of the present invention support itself in any position, it can also continually support up to 1,000 pounds in payload at any position.
In order to provide the necessary stabilization to the fire engine during use of the ladder, the fire engine is equipped with laterally extending stabilizers. In the present invention, it is preferred that the ladder be rotatably mounted to substantially a center portion of the fire engine. In this manner, longitudinal stability of the fire engine during ladder use may be provided by the cab and engine portion forward of the ladder, and the pump, water tank and other equipment located rearward of the ladder. At least one pair of lateral stabilizers are deigned to extend to either side of the fire engine, from a central portion thereof. The lateral stabilizers are designed to pass substantially through the turntable housing, and beneath the attachment point of the ladder. The lateral stabilizers are comprised of telescoping tubular sections that may be extended laterally outward by internal hydraulic cylinders. Each lateral stabilizer also has a leveling pad that may be extended vertically downward from an end portion of the lateral stabilizer to communicate with the ground. Each pair of lateral stabilizers is preferably arranged to form substantially a xe2x80x9cVxe2x80x9d shape. The ends of each stabilizer pair that are proximal to the turntable housing are adjacent to one another, with each stabilizer of the pair then diverging as the stabilizers extend laterally outward toward the respective side of the fire engine. This design allows the lateral stabilizers to reside in a compact arrangement when in a retracted position, but to provide stabilizing points over a significant area when extended. To accomplish the xe2x80x9cVxe2x80x9d shaped orientation of lateral stabilizers through the turntable housing, one pair of lateral stabilizers is disposed above the other pair. Thus, the leveling pads of one stabilizer pair will extend vertically downward a greater distance than the other pair.
While the lateral stabilizers safely permit the ladder to be fully extended and moved through any position, such movement may cause instability of the fire engine and resulting danger should one or more of the stabilizers be less than fully extended and in contact with the ground. Thus, the fire engine of the present invention also preferably monitors the position of each lateral stabilizer to determine the extent to which it has been extended. Preferably, this monitoring system is in communication with the control system of the ladder, and can cause movement thereof to be limited to a particular range based on the position of one or more of the lateral stabilizers.
Therefore, as can be seen, the fire engine of the present invention is especially useful in situations where access to significant heights is required, and further where such access may require that the extension ladder of the fire engine be placed into positions that would impart instability to known fire engines having such ladders. The stabilizers of the fire engine of the present invention allow the fire engine to remain stable even when the ladder is loaded and in its most unfavorable positionxe2x80x94extending substantially horizontally and laterally from the fire engine. The design of the lateral stabilizers permits support points to be arranged over a large area, thereby increasing the stability of the fire engine during use of the ladder, while also residing in a compact area while not in use, thereby providing space for other fire engine components or for storage.